This invention relates to devices that automatically feed wire at a constant pressure to a cut-off mechanism that consistently cuts an exact predetermined length of wire.
In mechanisms that remove taped individual electrical components from a reel in a sequential fashion for retaping of the components in a desired sequence for ultimate assembly to a circuit board, one of desired components that is often placed in the sequence is a jumper wire. Illustrations of machines of this type are shown in Woodman U.S. Pat. No. 4,119,206 and Romeo U.S. Pat. No. 3,669,309. These machines are software controlled and contain a plurality of taped electrical components that are sequentially removed from the tape, placed on a conveyor and subsequently retaped in the desired sequence for insertion into a printed circuit board.
In this assembly operation the machine will also carry a large roll of blank wire (called jumper wire) which will in the machine operation be supplied thru a feed roller mechanism to a cutter that cuts off a desired predetermined length of the jumper wire and places it on the conveyor for retaping in the proper sequence with the other electrical components. Such a taped jumper wire is illustrated in U.S. Pat. No. 3,971,193.
These reels of jumper wire are carried on the machine at a given station that has a spring biased idler pulley around which the wire passes, the wire then passes through straightening rollers and through driven feed rollers that are pulling the wire from the reel. After passing through the feed rollers, the wire is cut-off to a predetermined length and deposited on the sequencer conveyor at the desired time in the machine operation determined by the software controls. In this type of conventional wire feed, the feed rolls are driven a given revolution to supply a given length of wire to the cutter.
In this arrangement, because the wire is being pulled from the reel, the reel has a tendency to build up rotational inertia which varies the wire feed pressure to the feed rolls making it difficult for the feed rolls to supply during their feeding rotation a given exact length of wire to the cutter. Thus, it is desirable to develop a wire feeding mechanism wherein the action of the reel of wire is isolated from the feed rolls controlling the cut-off length of the wire. (This invention is illustrated in the environment of a component sequencing machine, however, the basic mechanism can be utilized in any machine in which a given exacting length of wire is desired--such as a staple forming machine. The invention is applicable to any mechanism wherein wire is removed from a large reel of wire and transferred to a cutter for consistently cutting exact lengths of the wire--wherein the action of a large reel of wire is isolated from the cutting mechanism so that it can supply consistent lengths of wire to be cut.)